Although those amendments may have "changed" the status of slavery. voting by far was the least of all the factors that changed slavery. If not for social pressure the 13th 14th and 15th amendment would have not been in place. And even after passing these amendments many states did not recognize thier existence. Thus further social action had to be implemented at the grassroots level.
I would argue that it is naive to assume that is was solely the white man who freed the slave through voting. The black slaves took their own initiative and if these amendments would have not been in place despite having fought in the civil war and having been told that they would be freed from bondage, you would have seen another uprising--a black revolution.
The civil rights movement is a demonstration of this. The laws despite these fore mentioned amendments did not truly free the slaves, because although they were free from physical slavery they were not free from economic slavery (similar to sweatshops of today). Also, segregation and other racist laws continued to exists. During the civil rights movement time, (which was not brought upon through voting) the politicans knew legislation or not, the opressed were going to have thier way. You cannot truly argue that voting was responsible for their liberation. Although people of color are still not entirely equal the gains in leaps acheived was through grassroots movements not through superficial voting. Voting merely made concrete the inevitable.
This is the same issue with women suffrage, women were not allowed to vote, how could they have gone from a non voting status to voting status. It seems that your argument would imply that it was through the men's voting that push forth the law that allowed women to vote. This would assume that the men were benevolent and "permitted" the women to vote. Yes in the least sense and most trivial it did, but if not from the strong women's movement these white men would have not felt the pressure to bring about such legislation. And if women were denied the right to vote, then you would have seen another civil action or possibly a womens revolution.
Now vote if you want, that is your problem, but peoples movement is not a "trendy thing." The only reason i would vote is for a political statement in the honor of people that won out certain rights in the several peoples movement.
But is it going to create social change? No, nothing major.